Brush-rigging for dynamo-electric machines



E. F. ANDREWS AND R. E. ACRE.

BRUSH meme FOR DYNAMO ELECTRIC MACHINES. APPLICATION FILED MAR. 28. 1919.

1,346,103, Patented July 13,1920.

v UNITED STATES PATENT OFFICE.

EDWARD I. ANDREWS, OF CHICAGO, AND RAY E. ACRE, oEwIIEATQ ILLINo s, ASSIGNORS T0 UNIVERSAL ENGINEERING COMPANY, or M Y oon, ILLINOIS,

A CORPORATION OF ILLINOIS.

BRUSH-RIGGING FOR DYNAMIC-ELECTRIC MA CHINES.

Specification of Letters Patent.

Patented. m 13,1920.

Application filed March 28, 1919. Serial No. 285,775.

chines, of which the following is a full;

clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

Our invention relates to brush rigging for dynamo electric machines, and is concerned with improvements in the attachment and location of the brushes and in the instrumentalities for maintaining the brushes in contact with the commutator orcollector ringwith which the brushes are associated.

Among the objects of our invention contemplates:

First: The provision of an efficient brush rigging that is of simple and rugged con struction, and one thatcan be easily and cheaply manufactured and. assembled.

Second: Mounting the brushes directly on pins driven into the metal framework of the machine in such a mannerthat the tendency of the brushes to vibrate or chatter when the commutator revolves is reduced to a minimum.

Third: The provision of means in the form ofa simple fiber bushing around the bases of the brush supporting pins foreffectively insulating the brushes from the framework by which the brush rigging is carried. 1

Fourth: The provision ofsimple and effective means .for limiting the motion of each of the brush arms under the action of its associated spring when the brush is worn to such an extent that further appreciable wear would allow the metal brush arm to come into contact with the commutator.

Fifth: A" pin disposed adjacent each of the brush arms arranged to serve as an abutment against which the spring forthat brush arm may act, said pins being easily insulated from the supporting frame and accurately located withlrespect to the pivots for the brush arms so thatthe springs may be made to act uniformly on the several brushes. We prefer that these pins shall function both as spring abutments and serve as the means for preventing the brush arms from at any time contacting with the commutator due to the wearing of the brushes.

Sixth: The disposition of the several brushes in such relation with respect tothc commutator and with respect to each other that the commutator may be cleaned and the brushes fitted and adjusted with the utmost facility.

Seventh: An arrangement of the several parts of the brush rigging such that to a maximum degree the movable parts are free from a tendency to stick due to the accumulation of oily or gummy substances at the brush arm pivots, the arrangement furthermore reducing to a minimum the possibility of short circuiting due to the accumulation of foreign matter between the brush supporting devices and the metal framework of the machine. I

Eighth LA simple andeifective means for connecting the usual jumpers or connecting wires to the insulated brushes.

Other objects of our invention will appear as this description progresses.

In the accompanying drawing illustrating our invention- Figurellis an elevational view illustrating a complete brush rigging embodying our invention;

Fig.- 2 is a top plan view of the same, a portion of the supporting frame being shown "in section more clearly to reveal the details of the brush mounting; and Fig. 3 is a fragmentary sectional view taken on the line AB of Fig. 1.

Similar characters of reference refer to similar parts throughout theseveral views. Referring firstto Fig. 1, we have illustrated at C a commutator carried by the armature of a dynamo electric machine, with which our improved brush rigging is associated. ,At F is illustrated a portion ofthe machine framework which is disposed adjacent the commutator and upon'and in which we prefer to mount the brush rigging of our invention. It will sufiice to state that that portion of the framework indicated at F may, if desired, be provided with ball or other suitable bearings forthe adjacent end ofthe armature shaft, such a bearing being indicated at F in Fig. 1. With these feaparticularly concerned, except in so far as this general arrangement adapts itself to the purposes of our invention.

In the drawings we have illustrated an arrangement comprising four carbon or other suitable brushes, namely the brushes B, B, of one polarity, which are insulated from the machine frame, as will presently appear, and brushes B, B, of the opposite polarity, which may be grounded to the machine frame.

Each of the brushes is mounted in a brush arm 4: in the form of a- U-shaped metal stamping conformed snugly to fit around the brush, thereby holding the brush parallel to the inner surfaces of the brush arm and at right angles to the commutator axis, this arrangement making it possible to employ a single brush screw 5 and its cooperating nut 6, to so hold the brush that it cannot turn to such a position that all of its engaging surface does not bear upon the commutator.

It will be noted that the parallel portions of each of the U-shaped brush arms are perforated, whereby the arm may be mounted upon a supporting pin. The pins whereon the brush arms of the insulated brushes B, B are mounted are indicated at 7, 7, and the supporting pins for the arms of the grounded brushes B, B, are indicated at 7, 7. The pins 7, 7 and 7, 7', are forced into holes of the proper size drilled into the frame F, it being noted that pins 7, 7 are insulated from the frame by the non-c011- ducting fiber bushings 8 into which the pins are tightly pressed. The pins 7, 7, are forced into the frame in direct contact therewith, thereby grounding brushes B, B. e prefer to have the insulating bushings 8 project a substantial distance from thesurface of the frame, thus preventing the possibility of the insulated brushes being grounded to the frame by their spring arms engaging the frame, or by reason of the accumulation of foreign matter between the spring arms and the frame.

Disposed upon each of the brush arm supporting pins and disposed between the parallel portions of the brush arm is a spring 9 hooked at 10 to engage the brush arm. The spring in each instance is provided with a loop 11 constituting an arm arranged to engage against a stop pin, the stop pins for the insulated brush springs being illustrated at 12, 12 and the stop pins for the grounded brush springs illustrated at 12, 12. The spring loop 11 is so shaped and disposed that when it is sprung over its associated stop pin the spring exerts a pressure upon its spring arm and holds the brush carried thereby in proper contact with the surface of the commutator.

It will be noted that each of the spring stop pins is disposed adjacent and parallel to its associated spring arm supporting pin and is fitted into the frame F in substantially the same way. Thus stop pins 12,12 are insulated from the frame by bushings 13, 13 to prevent brushes B, B from grounding to the frame through their spring stop pins, Whereas spring stop pins 12', 12 are forced directly into holes drilled in the frame.

Each of the spring stop pins 12, 12 and 12, 12 has a double function. In addition to serving as an abutment for its associated spring it serves as a means for limiting the movement of its associated spring arm toward the commutator, and thus prevents burning of the commutator and brush arm when the brush is worn to a considerable extent. In other words, each of the spring stop pins is so disposed with respect to its associated spring arm supporting pin that the metal of the spring arm cannot at any time engage the commutator. If it were not for this arrangement the wearing of the brush would eventually permit the spring arm to engage the commutator, re sulting in a serious burning of one or both elements.

It will be noted that each of the brush arms 1, 1 is retained upon its supporting pin 7 or 7, as the case may be, solely by a cotter pin 14:, thus making it extremely simplc to disassemble the rigging for any one of the brushes, for purposes of replacement, inspection or repair. Attention is further more directed to the fact that each of the insulated brush arm supporting pins 7, 7 is turned down and threaded at its outer end, and there provided with a nut 15 under which the usual jumper or other wire connection may be fastened. Pins 7, 7 being grounded to the frame of course need not be provided with terminals of this kind.

A distinctive feature of the brush rigging herein shown is the arrangement of the brushes and their supporting arms in such relation to each other and to the commutator as to permit ready access to the brushes and the several parts of the rigging, for cleaning and adjustment and to enable the cleaning of the commutator to be accomplished with great facility.

It will be noted that the brush arm supporting pins are all disposed very closely to a single line passing through the axis of the commutator. This is made possible by so disposing the pin and brush arms that the brushes B and B of each of the diametrically opposite pairs of insulated and grounded brushes lie on opposite sides of their supporting pivots. Thus in the present arrangement, assuming that the commutator rotates in the direction indicated by the arrow, the grounded brushes B, B trail or in other words project from their point of support in the direction of commutator rotation, whereas the insulated brushes B, B

stub, or in other Words project from their supporting pivots in a direction opposite to that of commutator rotation. We have found that the brushes Work equally Well Whether stubbing or trailing.

By disposing the brushes as just explained, it Will be seen that an extraordinarily large amount of commutator surface is exposed between the opposite pairs of brushes, thus facilitating access to the commutator for purposes of cleaning and repair, and furthermore ready access is had to the individual brushes, brush arms and brush arm springs, thus facilitating replacement, cleaning and adjustment of these parts.

Having thusdescribed the improved rigging of our invention, What We claim as new and desire to secure by Letters Patent of the United States is:

1. In combination With the commutator and framework of a dynamo electric machine, a brush rigging comprising a brush, a brush arm by Which the brush is carried, a brush arm supporting pin having one end thereof embedded in the frame and projecting therefrom in a line adjacent the commutator and parallel to the axis thereof,

said brush arm supporting pin constituting a pivot Whereon said brush arm is mounted,

the brush arm being removable over the outer end of the supporting pin, and a spring arranged and adapted to engage the brush arm to hold the brush in engagement With the commutator.

2; In combination With the commutator of a dynamo electric machine, two sets of diaeachpair projecting from its pivot in a line opposite the direction of commutator rotation, and the other brush arm of each pair projecting from its pivot in the direction of commutator rotation.

In Witness whereof We hereunto subscribe our names this 22d day of March, 1919.

EDWARD F. ANDREWVS, RAY E. ACRE.

, Witnesses:

A. G. MCCALEB, EDNA V. GUSTAFSON. 

